Sequential data optimized sub-regions in storage devices

ABSTRACT

Apparatus and methods are disclosed, including using a memory controller to partition a memory array into a first portion and a second portion, the first portion and second portion having non-overlapping logical block addressing (LBA) ranges. The memory controller assigns a first granularity of a first logical-to-physical (L2P) mapping table entry for the first portion of the memory array designated for a first usage, and a second granularity of a second L2P mapping table entry for the second portion of the memory array designated for a second usage, where the second granularity is not equal to the first granularity. The memory controller stores the first granularity and the second granularity in the memory array, and stores at least a portion of the first L2P mapping table entry and the second L2P mapping table entry in an L2P cache of the memory controller.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No. 17/702,217, filed Mar. 23, 2022, which is a continuation of U.S. application Ser. No. 17/129,087, filed Dec. 21, 2020, now issued as U.S. Pat. No. 11,294,585, which is a continuation of U.S. application Ser. No. 16/237,134, filed Dec. 31, 2018, now issued as U.S. Pat. No. 10,871,907, each of which is incorporated herein by reference in its entirety.

BACKGROUND

Memory devices are semiconductor circuits that provide electronic storage of data for a host system (e.g., a computer or other electronic device). Memory devices may be volatile or non-volatile. Volatile memory requires power to maintain data, and includes devices such as random-access memory (RAM), static random-access memory (SRAM), dynamic random-access memory (DRAM), or synchronous dynamic random-access memory (SDRAM), among others. Non-volatile memory can retain stored data when not powered, and includes devices such as flash memory, read-only memory (ROM), electrically erasable programmable ROM (EEPROM), erasable programmable ROM (EPROM), resistance variable memory, such as phase change random access memory (PCRAM), resistive random-access memory (RRAM), or magnetoresistive random access memory (MRAM), among others.

Host systems typically include a host processor, a first amount of main memory (e.g., often volatile memory, such as DRAM) to support the host processor, and one or more storage systems (e.g., often non-volatile memory, such as flash memory) that provide additional storage to retain data in addition to or separate from the main memory.

A storage system, such as a solid-state drive (SSD), can include a memory controller and one or more memory devices, including a number of dies or logical units (LUNs). In certain examples, each die can include a number of memory arrays and peripheral circuitry thereon, such as die logic or a die processor. The memory controller can include interface circuitry configured to communicate with a host device (e.g., the host processor or interface circuitry) through a communication interface (e.g., a bidirectional parallel or serial communication interface). The memory controller can receive commands or operations from the host system in association with memory operations or instructions, such as read or write operations to transfer data (e.g., user data and associated integrity data, such as error data or address data, etc.) between the memory devices and the host device, erase operations to erase data from the memory devices, perform drive management operations (e.g., data migration, garbage collection, block retirement), etc.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.

FIG. 1 illustrates an example host system including a host device and a storage system.

FIG. 2 illustrates an example method for providing data optimized sub-regions in a storage system.

FIGS. 3A-3D illustrate examples of mapping table regions in a storage system.

FIG. 4 illustrates an example schematic diagram of a 3D NAND architecture semiconductor memory array.

FIG. 5 illustrates an example block diagram of a memory module.

FIG. 6 illustrates an example block diagram of an information handling system.

DETAILED DESCRIPTION

Software (e.g., programs), instructions, operating systems (OS), and other data are typically stored on storage systems and accessed by main memory for use by a host processor. Main memory (e.g., RAM) is typically faster, more expensive, and a different type of memory device (e.g., volatile) than a majority of the memory devices of the storage system (e.g., non-volatile, such as an SSD, etc.). In addition to the main memory, host systems can include different levels of volatile memory, such as a group of static memory (e.g., a cache, often SRAM), often faster than the main memory, in certain examples, configured to operate at speeds close to or exceeding the speed of the host processor, but with lower density and higher cost. In other examples, more or less levels or quantities of main memory or static memory can be used, depending on desired host system performance and cost.

Flash memory devices, such as SSD, typically include one or more groups of one-transistor, floating gate memory cells. Two common types of flash memory array architectures include NAND and NOR architectures. The floating gate memory cells of the memory array are typically arranged in a matrix.

Performance of a NAND storage device is heavily influenced by the use of a flash translation layer (FTL) to map blocks of user data (logical block addressing or LBA) to physical addresses using a logical-to-physical (L2P) table. Current L2P tables use a four-byte physical address for each 4 KB chunk of user data, which results in a large mapping table that cannot fit into the L2P cache at one time. The present subject matter provides for partitioning some fraction of the storage device and operating the partition with a different mapping table granularity based on designated usage of the partition. By mapping a partition at a larger granularity, random read performance and sequential write performance will increase (as more of the mapping table will fit in the cache at a given time) for that partition, which will benefit software such as operating systems that can load more quickly and improve overall user experience.

Various embodiments provide for partitioning a user area of a storage device into multiple LBA ranges, and customizing the granularity of the L2P mapping table for each LBA range to a specific use case (or designated usage of the partitioned LBA range). An SRAM within the storage controller is customized for each L2P mapping table to optimize performance of each use case, in various embodiments. Thus, the present subject matter defines a custom L2P mapping granularity to various LBA ranges to produce customized random write and random read performances, and uses each LBA range for designated uses. For example, an operating system (O/S) or key application is placed in a region optimized for random read performance to improve boot-up times or load times, and less important or less commercially-advantaged applications are placed in a general-purpose region. Thus, partitions can be tuned for specific designated usages, such as streaming video or loading an O/S.

NAND flash-based storage devices require an FTL to map blocks of user data (LBAs) to physical addresses. In order to efficiently support small host writes, the normal granularity of an L2P mapping table is a single physical address entity for a small number of host LBAs, typically with a single physical address holding 4096 bytes of user data. With a four byte physical address for each 4 KB chunk of user data, the size of the mapping table is typically quite large. For most devices, having a large mapping table is prohibitive, and usually only a small subset of the mapping table is available within the storage controller at a time in an L2P cache.

In various embodiments, there is a tradeoff in the granularity of the mapping between efficiency of random write operations and efficiency of the L2P cache. In a first example, a 4 KB user data chunk (containing one or more LBAs) may be mapped to a 4 byte physical address. In a second example, an 8 KB user data chunk (containing twice as many LBAs as the 4 KB chunk) may be mapped to a 4 byte physical address. To execute a 4 KB user write in the first example, the data can be directly written and the mapping table updated with the new physical address. To execute a 4 KB user write in the second example, another 4 KB data chunk that belongs with the newly written data must be read from the storage media, joined to the new 4 KB data, and the newly constructed 8 KB chunk will be written to the memory, along with a mapping table update of a single entry. In the second example, the operation is a read-modify-write of the storage, which is less efficient than the first example, which is simply a write. Thus, the first example has a much better performance than the second example above. However, in the second example the L2P map cache can map twice as much space. With a 32 KB L2P cache size, the first example can store 32768/4=8192 physical address, each of which points to 4 KB, for a total mapped range of 32 MB. For the second example, 32 KB cache is enough to hold 8192 physical addresses, each of which points to 8 KB, for a total mapped range of 64 MB.

In various embodiments, the present subject matter partitions some fraction of the storage system and operates the partitions with different mapping table granularity. In one embodiment, with 256 GB of user storage area available, the first 16 GB of data (first region) can be mapped at a granularity of 256 KB for a single 4 byte physical address, and the remaining 240 GB (second region) can be mapped using a granularity of 4 KB for a single 4 byte physical address. The first region of the storage system mapped a large granularity will offer poor random write performance, as every write smaller than 256 KB involves a read-modify-write of 256 KB. The second region of the storage system mapped to a smaller granularity will offer better random write performance, as there is no read-modify-write penalty for a write down to 4 KB in size. On the other side of the trade-off, the entire 16 GB range of the first region can be mapped using only 256 KB of controller SRAM cache ((16*1024*1024*1024)/(256*1024)), whereas for the second region 256 KB will only map 256 MB of user area. While both the first region and the second region offer the same sequential read and write performance, the first region will offer superior random read performance as the entire mapping table for the first region can reside in SRAM at one time. For the second region, random read performance will suffer, as reads of the second region use a two-read sequence, one to load the appropriate portion of the mapping table to find the physical address associated with an LBA, and a second read to load the data.

By designating granularity to partitions for designated usages, the present subject matter will provide a significantly improved user experience and a more efficient use of controller SRAM mapping table resources. For example, the first region is best utilized for sequential writing, for example, the sequential load of an operating system and key applications that will be updated infrequently, and with large sequential writes. The first region will offer improved read performance, such that applications in the first region will have superior load times. This type of region would be useful for O/S in mobile devices, automotive devices or internet of things (IoT), in various embodiments. Mobile phone manufacturers can leverage this advantage by placing proprietary applications in the first region, so that they will outperform aftermarket applications that would by default reside in the second or other regions. The second region is best utilized for normal write use, offering a typical experience for which users are already accustomed.

In some embodiments, partitions can also be operated at different speeds by using a faster type of memory for certain partitions, making these advantages more pronounced. For example, a single-level cell memory (SLC) can be used instead of a triple-level cell memory (TLC) NAND, or 3D XPoint type memory can be used for designated partitions.

Various embodiments provide for definition of one or more regions of user area in a storage device, defined in a table of regions of non-overlapping LBA ranges. By using application-specific selection of mapping table granularity, the present subject matter trades controller L2P map SRAM resources for random write performance to optimize user experience for each application and each region of user area of the storage device. In various embodiments, when an LBA or group of LBAs is written to the storage device, the LBA is checked against the region table to determine the proper write granularity for the LBA, the appropriate read-modify-write is performed (if any), and appropriate mapping table updates are made depending on the attributes of the selected region. The present subject matter also provides for preservation of region attributes on garbage collection operations. Thus, reads and writes will be performed using the appropriate mapping table chunk size of the region when performing garbage collection. Because of limited memory controller resources for L2P map data, the granularity can be optimized for a particular device, a particular use case, and/or use model for marketplace advantaged performance.

In various embodiments of the present subject matter, varying granularities are stored permanently in the non-volatile memory array. Thus, multiple granularities can be used for regions of the storage device in a permanent mode of operation, and the granularities can be accessed by accessing the memory array. The granularities provide varying classes of configurable read service, in various embodiments. In various embodiments, multiple regions of the storage device can be assigned different granularities. In one example, two regions of the storage device are assigned different granularities. In another example, three regions of the storage device are assigned different granularities. Other numbers of regions of the storage device can be assigned different granularities without departing from the scope of the present subject matter. Some embodiments are targeted to devices without enough DRAM to hold an entire L2P map.

Aspects of the present disclosure are directed to a storage system including a memory array, a random access memory configured to store at least a portion of one or more logical-to-physical (L2P) mapping tables, and a memory controller. The memory controller is programmed to perform operations including: partitioning the memory array into a first portion and a second portion, the first portion and second portion having non-overlapping logical block addressing (LBA) ranges; assigning a first granularity of a first L2P mapping table entry for the first portion of the memory array designated for a first usage; assigning a second granularity of a second L2P mapping table entry for the second portion of the memory array designated for a second usage, where the second granularity is not equal to the first granularity; and storing at least a portion of the first L2P mapping table entry and the second L2P mapping table entry in the random access memory.

FIG. 1 illustrates an example system (e.g., a host system) 100 including a host device 105 and a storage system 110 configured to communicate over a communication interface (I/F) 115 (e.g., a bidirectional parallel or serial communication interface). The host device 105 can include a host processor 106 (e.g., a host central processing unit (CPU) or other processor or processing device) or other host circuitry (e.g., a memory management unit (MMU), interface circuitry, assessment circuitry 107, etc.). In certain examples, the host device 105 can include a main memory 108 (e.g., DRAM, etc.) and optionally, a static memory 109, to support operation of the host processor 106.

The storage system 110 can include a universal flash storage (UFS) device, an embedded MMC (eMMC™) device, or one or more other memory devices. For example, if the storage system 110 includes a UFS device, the communication interface 115 can include a serial bidirectional interface, such as defined in one or more Joint Electron Device Engineering Council (JEDEC) standards (e.g., JEDEC standard D223D (JESD223D), commonly referred to as JEDEC UFS Host Controller Interface (UFSHCI) 3.0, etc.). In another example, if the storage system 110 includes an eMMC device, the communication interface 115 can include a number of parallel bidirectional data lines (e.g., DAT[7:0]) and one or more command lines, such as defined in one or more JEDEC standards (e.g., JEDEC standard D84-B51 (JESD84-A51), commonly referred to as JEDEC eMMC standard 5.1, etc.). In other examples, the storage system 110 can include one or more other memory devices, or the communication interface 115 can include one or more other interfaces, depending on the host device 105 and the storage system 110.

The storage system 110 can include a memory controller 111, a random access memory (or cache) 113 and a non-volatile memory 112. In an example, the non-volatile memory can include a number of memory devices (e.g., dies or LUNs), such as one or more flash memory devices, etc., each including periphery circuitry thereon, and controlled by the memory controller 111.

Flash memory devices typically include one or more groups of one-transistor, floating gate memory cells. Two common types of flash memory array architectures include NAND and NOR architectures. The floating gate memory cells of the memory array are typically arranged in a matrix. The gates of each memory cell in a row of the array are coupled to an access line (e.g., a word line). In NOR architecture, the drains of each memory cell in a column of the array are coupled to a data line (e.g., a bit line). In NAND architecture, the drains of each memory cell in a column of the array are coupled together in series, source to drain, between a source line and a bit line.

Each memory cell in a NOR, NAND, 3D Cross Point (Xpoint), Holographic RAM (HRAM), MRAM, or one or more other architecture semiconductor memory array can be programmed individually or collectively to one or a number of programmed states. A single-level cell (SLC) can represent one bit of data per cell in one of two programmed states (e.g., 1 or 0). A multi-level cell (MLC) can represent two or more bits of data per cell in a number of programmed states (e.g., 2^(n), where n is the number of bits of data). In certain examples, MLC can refer to a memory cell that can store two bits of data in one of 4 programmed states. A triple-level cell (TLC) can represent three bits of data per cell in one of 8 programmed states. A quad-level cell (QLC) can represent four bits of data per cell in one of 16 programmed states. MLC is used herein in its broader context, to refer to any memory cell that can store more than one bit of data per cell (i.e., that can represent more than two programmed states), including TLC and QLC, etc.

The storage system 110 can include a multimedia card (MMC) solid-state storage device (e.g., micro secure digital (SD) cards, etc.). MMC devices include a number of parallel interfaces (e.g., an 8-bit parallel interface) with a host device 105, and are often removable and separate components from the host device. In contrast, embedded MMC (eMMC) devices are attached to a circuit board and considered a component of the host device, with read speeds that rival serial ATA (SATA) based SSD devices. As demand for mobile device performance continues to increase, such as to fully enable virtual or augmented-reality devices, utilize increasing networks speeds, etc., storage systems have shifted from parallel to serial communication interfaces. UFS devices, including controllers and firmware, communicate with a host device using a low-voltage differential signaling (LVDS) serial interface with dedicated read/write paths, further advancing read/write speeds between a host device and a storage system.

In three-dimensional (3D) architecture semiconductor memory device technology, vertical floating gate or charge trapping storage structures can be stacked, increasing the number of tiers, physical pages, and accordingly, the density of memory cells in a memory device.

Data is often stored arbitrarily on the storage system as small units. Even if accessed as a single unit, data can be received in small, random 4-16k single file reads (e.g., 60%-80% of operations are smaller than 16k). It is difficult for a user and even kernel applications to indicate that data should be stored as one sequential cohesive unit. File systems are typically designed to optimize space usage, and not sequential retrieval space.

The memory controller 111 can receive instructions from the host device 105, and can communicate with the non-volatile memory 112, such as to transfer data to (e.g., write or erase) or from (e.g., read) one or more of the memory cells of the non-volatile memory array 112. The memory controller 111 can include, among other things, circuitry or firmware, such as a number of components or integrated circuits. For example, the memory controller 111 can include one or more memory control units, circuits, or components configured to control access across the memory array and to provide a translation layer between the host device 105 and the storage system 100.

The non-volatile memory array 112 (e.g., a 3D NAND architecture semiconductor memory array) can include a number of memory cells arranged in, for example, a number of devices, planes, blocks, or physical pages. As one example, a TLC memory device can include 18,592 bytes (B) of data per page, 1536 pages per block, 548 blocks per plane, and 4 planes per device. As another example, an MLC memory device can include 18,592 bytes (B) of data per page, 1024 pages per block, 548 blocks per plane, and 4 planes per device, but with half the required write time and twice the program/erase (P/E) cycles as a corresponding TLC memory device. Other examples can include other numbers or arrangements.

FIG. 2 illustrates an example method 200 for providing data optimized sub-regions in a storage system. The method 200 includes partitioning, by a memory controller, a memory array into a first portion and a second portion, the first portion and second portion having non-overlapping logical block addressing (LBA) ranges, at 202, and assigning, by the memory controller, a first granularity of a first L2P mapping table entry for the first portion of the memory array designated for a first usage, at 204. The method 200 further includes assigning, by the memory controller, a second granularity of a second L2P mapping table entry for the second portion of the memory array designated for a second usage, where the second granularity is not equal to the first granularity, at 206, storing, by the memory controller, the first granularity and the second granularity in the memory array, at 208, and storing, by the memory controller, at least a portion of the first L2P mapping table entry and the second L2P mapping table entry in an L2P cache of the memory controller, at 210.

FIGS. 3A-3D illustrate examples of mapping table regions in a storage system. In various embodiments, the region table map is stored at the memory controller and used as a look-up for determining granularity of regions to be used for storage or retrieval. In the depicted embodiment, region 4 in FIG. 3D is used for O/S or streaming, as this region will exhibit superior read performance. Region 1 in FIG. 3A will exhibit more normal performance, and can be used for smaller programs or data that will not have the performance demands of data such as O/S or streaming. In various embodiments, a user can control what type of region to write data to, depending on desired performance and availability. The present subject matter customizes data regions of a storage system based on expected workload of stored data in each region, in various embodiments.

FIG. 4 illustrates an example schematic diagram of a 3D NAND architecture semiconductor memory array 400 including a number of strings of memory cells (e.g., first-third A₀ memory strings 405A₀-407A₀, first-third A_(n) memory strings 405A_(n)-407A_(n), first-third B₀ memory strings 405B₀-407B₀, first-third B_(n) memory strings 405B-407B, etc.), organized in blocks (e.g., block A 401A, block B 401B, etc.) and sub-blocks (e.g., sub-block A₀ 401A₀, sub-block A_(n) 401A_(n), sub-block B₀ 401B₀, sub-block B_(n) 401B_(n), etc.). The memory array 400 represents a portion of a greater number of similar structures that would typically be found in a block, device, or other unit of a memory device.

Each string of memory cells includes a number of tiers of charge storage transistors (e.g., floating gate transistors, charge-trapping structures, etc.) stacked in the Z direction, source to drain, between a source line (SRC) 435 or a source-side select gate (SGS) (e.g., first-third A₀ SGS 431A₀-433A₀, first-third A_(n) SGS 431A_(n)-433A_(n), first-third B₀ SGS 431B₀-433B₀, first-third B_(n) SGS 431B_(n)-433B_(n) etc.) and a drain-side select gate (SGD) (e.g., first-third A₀ SGD 426A₀-428A₀, first-third A_(n) SGD 426A₀-428A₀, first-third B₀ SGD 426B₀-428B₀, first-third B_(n) SGD 426B_(n)-428B_(n), etc.). Each string of memory cells in the 3D memory array can be arranged along the X direction as data lines (e.g., bit lines (BL) BL0-BL6 420-422), and along the Y direction as physical pages.

Within a physical page, each tier represents a row of memory cells, and each string of memory cells represents a column. A sub-block can include one or more physical pages. A block can include a number of sub-blocks (or physical pages) (e.g., 128, 256, 384, etc.). Although illustrated herein as having two blocks, each block having two sub-blocks, each sub-block having a single physical page, each physical page having three strings of memory cells, and each string having 8 tiers of memory cells, in other examples, the memory array 400 can include more or fewer blocks, sub-blocks, physical pages, strings of memory cells, memory cells, or tiers. For example, each string of memory cells can include more or fewer tiers (e.g., 16, 32, 64, 128, etc.), as well as one or more additional tiers of semiconductor material above or below the charge storage transistors (e.g., select gates, data lines, etc.), as desired. As an example, a 48 GB TLC NAND memory device can include 18,592 bytes (B) of data per page (16,384+2208 bytes), 1536 pages per block, 548 blocks per plane, and 4 or more planes per device.

Each memory cell in the memory array 400 includes a control gate (CG) coupled to (e.g., electrically or otherwise operatively connected to) an access line (e.g., word lines (WL) WL0 ₀-WL7 ₀ 410A-417A, WL0 ₁-WL7 ₁ 410B-417B, etc.), which collectively couples the control gates (CGs) across a specific tier, or a portion of a tier, as desired. Specific tiers in the 3D memory array, and accordingly, specific memory cells in a string, can be accessed or controlled using respective access lines. Groups of select gates can be accessed using various select lines. For example, first-third A₀ SGD 426A₀-428A₀ can be accessed using an A₀ SGD line SGDA₀ 425A₀, first-third A_(n) SGD 426A_(n)-428A_(n) can be accessed using an SGD line SGDA₀ 425A₀, first-third B₀ SGD 426B₀-428B₀ can be accessed using an B₀ SGD line SGDB₀ 425B₀, and first-third B_(n) SGD 426B_(a)-428B_(n) can be accessed using an B_(n) SGD line SGDB₀ 425B_(a). First-third A₀ SGS 431A₀-433A₀ and first-third A_(n) SGS 431A_(n)-433A_(n) can be accessed using a gate select line SGS₀ 430A, and first-third B₀ SGS 431B₀-433B₀ and first-third B_(n) SGS 431B_(n)-433B_(n) can be accessed using a gate select line SGS₁ 430B.

In an example, the memory array 400 can include a number of levels of semiconductor material (e.g., polysilicon, etc.) configured to couple the control gates (CGs) of each memory cell or select gate (or a portion of the CGs or select gates) of a respective tier of the array. Specific strings of memory cells in the array can be accessed, selected, or controlled using a combination of bit lines (BLs) and select gates, etc., and specific memory cells at one or more tiers in the specific strings can be accessed, selected, or controlled using one or more access lines (e.g., word lines).

In a NAND architecture semiconductor memory array, the state of a selected memory cell can be accessed by sensing a current or voltage variation associated with a particular data line containing the selected memory cell. The memory array 400 can be accessed (e.g., by a control circuit, one or more processors, digital logic, etc.) using one or more drivers. In an example, one or more drivers can activate a specific memory cell, or set of memory cells, by driving a particular potential to one or more data lines (e.g., bit lines BL0-BL2), access lines (e.g., word lines WL0-WL7), or select gates, depending on the type of operation desired to be performed on the specific memory cell or set of memory cells.

To program or write data to a memory cell, a programming voltage (Vpgm) (e.g., one or more programming pulses, etc.) can be applied to selected word lines (e.g., WL4 ₀), and thus, to a control gate of each memory cell coupled to the selected word lines. Programming pulses can begin, for example, at or near 15V, and, in certain examples, can increase in magnitude during each programming pulse application. While the program voltage is applied to the selected word lines, a potential, such as a ground potential (e.g., Vss), can be applied to the data lines (e.g., bit lines) and substrates (and thus the channels, between the sources and drains) of the memory cells targeted for programming, resulting in a charge transfer (e.g., direct injection or Fowler-Nordheim (FN) tunneling, etc.) from the channels to the floating gates of the targeted memory cells.

In contrast, a pass voltage (Vpass) can be applied to one or more word lines having memory cells that are not targeted for programming, or an inhibit voltage (e.g., Vcc) can be applied to data lines (e.g., bit lines) having memory cells that are not targeted for programming, for example, to inhibit charge from being transferred from the channels to the floating gates of such non-targeted memory cells. The pass voltage can be variable, depending, for example, on the proximity of the applied pass voltages to a word line targeted for programming. The inhibit voltage can include a supply voltage (Vcc), such as a voltage from an external source or supply (e.g., a battery, an AC-to-DC converter, etc.), relative to a ground potential (e.g., Vss).

As an example, if a programming voltage (e.g., 15V or more) is applied to a specific word line, such as WL4 ₀, a pass voltage of 10V can be applied to one or more other word lines, such as WL3 ₀, WL5 ₀, etc., to inhibit programming of non-targeted memory cells, or to retain the values stored on such memory cells not targeted for programming. As the distance between an applied program voltage and the non-targeted memory cells increases, the pass voltage required to refrain from programming the non-targeted memory cells can decrease. For example, where a programming voltage of 15V is applied to WL4 ₀, a pass voltage of 10V can be applied to WL3 ₀ and WL5 ₀, a pass voltage of 8V can be applied to WL2 ₀ and WL6 ₀, a pass voltage of 7V can be applied to WL1 ₀ and WL7 ₀, etc. In other examples, the pass voltages, or number of word lines, etc., can be higher or lower, or more or less.

Sense amplifiers can be coupled to one or more of the data lines (e.g., first, second, or third bit lines (BL0-BL2) 420-422), can detect the state of each memory cell in respective data lines by sensing a voltage or current on a particular data line.

Between applications of one or more programming pulses (e.g., Vpgm), a verify operation can be performed to determine if a selected memory cell has reached its intended programmed state. If the selected memory cell has reached its intended programmed state, it can be inhibited from further programming. If the selected memory cell has not reached its intended programmed state, additional programming pulses can be applied. If the selected memory cell has not reached its intended programmed state after a particular number of programming pulses (e.g., a maximum number), the selected memory cell, or a string, block, or page associated with such selected memory cell, can be marked as defective.

To erase a memory cell or a group of memory cells (e.g., erasure is typically performed in blocks or sub-blocks), an erasure voltage (Vers) (e.g., typically Vpgm) can be applied to the substrates (and thus the channels, between the sources and drains) of the memory cells targeted for erasure (e.g., using one or more bit lines, select gates, etc.), while the word lines of the targeted memory cells are kept at a potential, such as a ground potential (e.g., Vss), resulting in a charge transfer (e.g., direct injection or Fowler-Nordheim (FN) tunneling, etc.) from the floating gates of the targeted memory cells to the channels.

FIG. 5 illustrates an example block diagram of a memory device 500 including a memory array 502 having a plurality of memory cells 504, and one or more circuits or components to provide communication with, or perform one or more memory operations on, the memory array 502. Although shown with a single memory array 502, in other examples, one or more additional memory arrays, dies, or LUNs can be included herein. In certain examples, in a storage system having a number of dies or LUNs, the memory device 500 can represent a block diagram of circuits and components for each die or LUN. The memory device 500 can include a row decoder 512, a column decoder 514, sense amplifiers 520, a page buffer 522, a selector 524, an input/output (I/O) circuit 526, and a memory control unit 530.

The memory cells 504 of the memory array 502 can be arranged in blocks, such as first and second blocks 502A, 502B. Each block can include sub-blocks. For example, the first block 502A can include first and second sub-blocks 502A₀, 502A_(n), and the second block 502B can include first and second sub-blocks 502B₀, 502B_(n). Each sub-block can include a number of physical pages, each page including a number of memory cells 504. Although illustrated herein as having two blocks, each block having two sub-blocks, and each sub-block having a number of memory cells 504, in other examples, the memory array 502 can include more or fewer blocks, sub-blocks, memory cells, etc. In other examples, the memory cells 504 can be arranged in a number of rows, columns, pages, sub-blocks, blocks, etc., and accessed using, for example, access lines 506, first data lines 510, or one or more select gates, source lines, etc.

The memory control unit 530 can control memory operations of the memory device 500 according to one or more signals or instructions received on control lines 532, including, for example, one or more clock signals or control signals that indicate a desired operation (e.g., write, read, erase, etc.), or address signals (A0-AX) received on one or more address lines 516. One or more devices external to the memory device 500 can control the values of the control signals on the control lines 532, or the address signals on the address line 516. Examples of devices external to the memory device 500 can include, but are not limited to, a host, a memory controller, a processor, or one or more circuits or components not illustrated in FIG. 5 .

The memory device 500 can use access lines 506 and first data lines 510 to transfer data to (e.g., write or erase) or from (e.g., read) one or more of the memory cells 504. The row decoder 512 and the column decoder 514 can receive and decode the address signals (A0-AX) from the address line 516, can determine which of the memory cells 504 are to be accessed, and can provide signals to one or more of the access lines 506 (e.g., one or more of a plurality of word lines (WL0-WLm)) or the first data lines 510 (e.g., one or more of a plurality of bit lines (BL0-BLn)), such as described above.

The memory device 500 can include sense circuitry, such as the sense amplifiers 520, configured to determine the values of data on (e.g., read), or to determine the values of data to be written to, the memory cells 504 using the first data lines 510. For example, in a selected string of memory cells 504, one or more of the sense amplifiers 520 can read a logic level in the selected memory cell 504 in response to a read current flowing in the memory array 502 through the selected string to the data lines 510.

One or more devices external to the memory device 500 can communicate with the memory device 500 using the I/O lines (DQ0-DQN) 508, address lines 516 (A0-AX), or control lines 532. The input/output (I/O) circuit 526 can transfer values of data in or out of the memory device 500, such as in or out of the page buffer 522 or the memory array 502, using the I/O lines 508, according to, for example, the control lines 532 and address lines 516. The page buffer 522 can store data received from the one or more devices external to the memory device 500 before the data is programmed into relevant portions of the memory array 502, or can store data read from the memory array 502 before the data is transmitted to the one or more devices external to the memory device 500.

The column decoder 514 can receive and decode address signals (A0-AX) into one or more column select signals (CSEL1-CSELn). The selector 524 (e.g., a select circuit) can receive the column select signals (CSEL1-CSELn) and select data in the page buffer 522 representing values of data to be read from or to be programmed into memory cells 504. Selected data can be transferred between the page buffer 522 and the I/O circuit 526 using second data lines 518.

The memory control unit 530 can receive positive and negative supply signals, such as a supply voltage (Vcc) 534 and a negative supply (Vss) 536 (e.g., a ground potential), from an external source or supply (e.g., an internal or external battery, an AC-to-DC converter, etc.). In certain examples, the memory control unit 530 can include a regulator 528 to internally provide positive or negative supply signals.

FIG. 6 illustrates a block diagram of an example machine (e.g., a host system) 600 upon which any one or more of the techniques (e.g., methodologies) discussed herein may perform. In alternative embodiments, the machine 600 may operate as a standalone device or may be connected (e.g., networked) to other machines. In a networked deployment, the machine 600 may operate in the capacity of a server machine, a client machine, or both in server-client network environments. In an example, the machine 600 may act as a peer machine in peer-to-peer (P2P) (or other distributed) network environment. The machine 600 may be a personal computer (PC), a tablet PC, a set-top box (STB), a personal digital assistant (PDA), a mobile telephone, a web appliance, an IoT device, automotive system, or any machine capable of executing instructions (sequential or otherwise) that specify actions to be taken by that machine. Further, while only a single machine is illustrated, the term “machine” shall also be taken to include any collection of machines that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein, such as cloud computing, software as a service (SaaS), other computer cluster configurations.

Examples, as described herein, may include, or may operate by, logic, components, devices, packages, or mechanisms. Circuitry is a collection (e.g., set) of circuits implemented in tangible entities that include hardware (e.g., simple circuits, gates, logic, etc.). Circuitry membership may be flexible over time and underlying hardware variability. Circuitries include members that may, alone or in combination, perform specific tasks when operating. In an example, hardware of the circuitry may be immutably designed to carry out a specific operation (e.g., hardwired). In an example, the hardware of the circuitry may include variably connected physical components (e.g., execution units, transistors, simple circuits, etc.) including a computer-readable medium physically modified (e.g., magnetically, electrically, moveable placement of invariant massed particles, etc.) to encode instructions of the specific operation. In connecting the physical components, the underlying electrical properties of a hardware constituent are changed, for example, from an insulator to a conductor or vice versa. The instructions enable participating hardware (e.g., the execution units or a loading mechanism) to create members of the circuitry in hardware via the variable connections to carry out portions of the specific tasks when in operation. Accordingly, the computer-readable medium is communicatively coupled to the other components of the circuitry when the device is operating. In an example, any of the physical components may be used in more than one member of more than one circuitry. For example, under operation, execution units may be used in a first circuit of a first circuitry at one point in time and reused by a second circuit in the first circuitry, or by a third circuit in a second circuitry at a different time.

The machine (e.g., computer system, a host system, etc.) 600 may include a processing device 602 (e.g., a hardware processor, a central processing unit (CPU), a graphics processing unit (GPU), a hardware processor core, or any combination thereof, etc.), a main memory 604 (e.g., read-only memory (ROM), dynamic random-access memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM), etc.), a static memory 606 (e.g., static random-access memory (SRAM), etc.), and a storage system 618, some or all of which may communicate with each other via a communication interface (e.g., a bus) 630.

The processing device 602 can represent one or more general-purpose processing devices such as a microprocessor, a central processing unit, or the like. More particularly, the processing device can be a complex instruction set computing (CISC) microprocessor, reduced instruction set computing (RISC) microprocessor, very long instruction word (VLIW) microprocessor, or a processor implementing other instruction sets, or processors implementing a combination of instruction sets. The processing device 602 can also be one or more special-purpose processing devices such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), network processor, or the like. The processing device 602 can be configured to execute instructions 626 for performing the operations and steps discussed herein. The computer system 600 can further include a network interface device 608 to communicate over a network 620.

The storage system 618 can include a machine-readable storage medium (also known as a computer-readable medium) on which is stored one or more sets of instructions 626 or software embodying any one or more of the methodologies or functions described herein. The instructions 626 can also reside, completely or at least partially, within the main memory 604 or within the processing device 602 during execution thereof by the computer system 600, the main memory 604 and the processing device 602 also constituting machine-readable storage media.

The term “machine-readable storage medium” should be taken to include a single medium or multiple media that store the one or more sets of instructions, or any medium that is capable of storing or encoding a set of instructions for execution by the machine and that cause the machine to perform any one or more of the methodologies of the present disclosure. The term “machine-readable storage medium” shall accordingly be taken to include, but not be limited to, solid-state memories, optical media, and magnetic media. In an example, a massed machine-readable medium comprises a machine-readable medium with a plurality of particles having invariant (e.g., rest) mass. Accordingly, massed machine-readable media are not transitory propagating signals. Specific examples of massed machine-readable media may include: non-volatile memory, such as semiconductor memory devices (e.g., Electrically Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM)) and flash memory devices; magnetic disks, such as internal hard disks and removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks.

The machine 600 may further include a display unit, an alphanumeric input device (e.g., a keyboard), and a user interface (UI) navigation device (e.g., a mouse). In an example, one or more of the display unit, the input device, or the UI navigation device may be a touch screen display. The machine a signal generation device (e.g., a speaker), or one or more sensors, such as a global positioning system (GPS) sensor, compass, accelerometer, or one or more other sensor. The machine 600 may include an output controller, such as a serial (e.g., universal serial bus (USB), parallel, or other wired or wireless (e.g., infrared (IR), near field communication (NFC), etc.) connection to communicate or control one or more peripheral devices (e.g., a printer, card reader, etc.).

The instructions 626 (e.g., software, programs, an operating system (OS), etc.) or other data are stored on the storage system 618 can be accessed by the main memory 604 for use by the processing device 602. The main memory 604 (e.g., DRAM) is typically fast, but volatile, and thus a different type of storage than the storage system 618 (e.g., an SSD), which is suitable for long-term storage, including while in an “off” condition. The instructions 626 or data in use by a user or the machine 600 are typically loaded in the main memory 604 for use by the processing device 602. When the main memory 604 is full, virtual space from the storage system 618 can be allocated to supplement the main memory 604; however, because the storage system 618 device is typically slower than the main memory 604, and write speeds are typically at least twice as slow as read speeds, use of virtual memory can greatly reduce user experience due to storage system latency (in contrast to the main memory 604, e.g., DRAM). Further, use of the storage system 618 for virtual memory can greatly reduce the usable lifespan of the storage system 618.

The instructions 624 may further be transmitted or received over a network 620 using a transmission medium via the network interface device 608 utilizing any one of a number of transfer protocols (e.g., frame relay, internet protocol (IP), transmission control protocol (TCP), user datagram protocol (UDP), hypertext transfer protocol (HTTP), etc.). Example communication networks may include a local area network (LAN), a wide area network (WAN), a packet data network (e.g., the Internet), mobile telephone networks (e.g., cellular networks), Plain Old Telephone (POTS) networks, and wireless data networks (e.g., Institute of Electrical and Electronics Engineers (IEEE) 802.11 family of standards known as Wi-Fi®, IEEE 802.16 family of standards known as WiMax®), IEEE 802.15.4 family of standards, peer-to-peer (P2P) networks, among others. In an example, the network interface device 608 may include one or more physical jacks (e.g., Ethernet, coaxial, or phone jacks) or one or more antennas to connect to the network 620. In an example, the network interface device 608 may include a plurality of antennas to wirelessly communicate using at least one of single-input multiple-output (SIMO), multiple-input multiple-output (MIMO), or multiple-input single-output (MISO) techniques. The term “transmission medium” shall be taken to include any intangible medium that is capable of storing, encoding, or carrying instructions for execution by the machine 600, and includes digital or analog communications signals or other intangible medium to facilitate communication of such software.

The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples”. Such examples can include elements in addition to those shown or described. However, the present inventor also contemplates examples in which only those elements shown or described are provided. Moreover, the present inventor also contemplates examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.

All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.

In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein”. Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.

In various examples, the components, controllers, processors, units, engines, or tables described herein can include, among other things, physical circuitry or firmware stored on a physical device. As used herein, “processor” means any type of computational circuit such as, but not limited to, a microprocessor, a microcontroller, a graphics processor, a digital signal processor (DSP), or any other type of processor or processing circuit, including a group of processors or multi-core devices.

The term “horizontal” as used in this document is defined as a plane parallel to the conventional plane or surface of a substrate, such as that underlying a wafer or die, regardless of the actual orientation of the substrate at any point in time. The term “vertical” refers to a direction perpendicular to the horizontal as defined above. Prepositions, such as “on,” “over,” and “under” are defined with respect to the conventional plane or surface being on the top or exposed surface of the substrate, regardless of the orientation of the substrate; and while “on” is intended to suggest a direct contact of one structure relative to another structure which it lies “on” (in the absence of an express indication to the contrary); the terms “over” and “under” are expressly intended to identify a relative placement of structures (or layers, features, etc.), which expressly includes—but is not limited to—direct contact between the identified structures unless specifically identified as such. Similarly, the terms “over” and “under” are not limited to horizontal orientations, as a structure may be “over” a referenced structure if it is, at some point in time, an outermost portion of the construction under discussion, even if such structure extends vertically relative to the referenced structure, rather than in a horizontal orientation.

The terms “wafer” and “substrate” are used herein to refer generally to any structure on which integrated circuits are formed, and also to such structures during various stages of integrated circuit fabrication. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the various embodiments is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.

Various embodiments according to the present disclosure and described herein include memory utilizing a vertical structure of memory cells (e.g., NAND strings of memory cells). As used herein, directional adjectives will be taken relative a surface of a substrate upon which the memory cells are formed (i.e., a vertical structure will be taken as extending away from the substrate surface, a bottom end of the vertical structure will be taken as the end nearest the substrate surface and a top end of the vertical structure will be taken as the end farthest from the substrate surface).

As used herein, directional adjectives, such as horizontal, vertical, normal, parallel, perpendicular, etc., can refer to relative orientations, and are not intended to require strict adherence to specific geometric properties, unless otherwise noted. For example, as used herein, a vertical structure need not be strictly perpendicular to a surface of a substrate, but may instead be generally perpendicular to the surface of the substrate, and may form an acute angle with the surface of the substrate (e.g., between 60 and 120 degrees, etc.).

In some embodiments described herein, different doping configurations may be applied to a select gate source (SGS), a control gate (CG), and a select gate drain (SGD), each of which, in this example, may be formed of or at least include polysilicon, with the result such that these tiers (e.g., polysilicon, etc.) may have different etch rates when exposed to an etching solution. For example, in a process of forming a monolithic pillar in a 3D semiconductor device, the SGS and the CG may form recesses, while the SGD may remain less recessed or even not recessed. These doping configurations may thus enable selective etching into the distinct tiers (e.g., SGS, CG, and SGD) in the 3D semiconductor device by using an etching solution (e.g., tetramethylammonium hydroxide (TMCH)).

Operating a memory cell, as used herein, includes reading from, writing to, or erasing the memory cell. The operation of placing a memory cell in an intended state is referred to herein as “programming,” and can include both writing to or erasing from the memory cell (i.e., the memory cell may be programmed to an erased state).

It will be understood that when an element is referred to as being “on,” “connected to” or “coupled with” another element, it can be directly on, connected, or coupled with the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to” or “directly coupled with” another element, there are no intervening elements or layers present. If two elements are shown in the drawings with a line connecting them, the two elements can be either be coupled, or directly coupled, unless otherwise indicated.

Method examples described herein can be machine or computer-implemented at least in part. Some examples can include a computer-readable medium or machine-readable medium encoded with instructions operable to configure an electronic device to perform methods as described in the above examples. An implementation of such methods can include code, such as microcode, assembly language code, a higher-level language code, or the like. Such code can include computer readable instructions for performing various methods. The code may form portions of computer program products. Further, the code can be tangibly stored on one or more volatile or non-volatile tangible computer-readable media, such as during execution or at other times. Examples of these tangible computer-readable media can include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (e.g., compact disks and digital video disks), magnetic cassettes, memory cards or sticks, random access memories (RAMs), read only memories (ROMs), and the like.

Example 1 is a storage system comprising: a memory array; a random access memory configured to store at least a portion of one or more logical-to-physical (L2P) mapping tables; and a memory controller, wherein the memory controller is programmed to perform operations including: partitioning the memory array into a first portion and a second portion, the first portion and second portion having non-overlapping logical block addressing (LBA) ranges; assigning a first granularity of a first L2P mapping table entry for the first portion of the memory array designated for a first usage; assigning a second granularity of a second L2P mapping table entry for the second portion of the memory array designated for a second usage, where the second granularity is not equal to the first granularity; storing the first granularity and the second granularity in the memory array; and storing at least a portion of the first L2P mapping table entry and the second L2P mapping table entry in the random access memory.

In Example 2, the subject matter of Example 1 is optionally configured such that the first and second granularity are stored in a region table in the controller.

In Example 3, the subject matter of Example 1 is optionally configured such that the first granularity is greater than the second granularity.

In Example 4, the subject matter of Example 1 is optionally configured such that the second granularity is greater than the first granularity.

In Example 5, the subject matter of any of Examples 1-4 is optionally configured such that the first portion and the second portion are different memory types.

In Example 6, the subject matter of any of Examples 1-5 is optionally configured such that partitioning the memory array into a first portion and a second portion includes partitioning the memory array at startup.

In Example 7, the subject matter of any of Examples 1-5 is optionally configured such that partitioning the memory array into a first portion and a second portion includes partitioning the memory array during runtime.

In Example 8, the subject matter of any of Examples 1-5 is optionally configured such that partitioning the memory array into a first portion and a second portion includes partitioning the memory array at startup and re-partitioning the memory array during runtime.

Example 9 is a method comprising: partitioning, by a memory controller, a memory array into a first portion and a second portion, the first portion and second portion having non-overlapping logical block addressing (LBA) ranges; assigning, by the memory controller, a first granularity of a first logical-to-physical (L2P) mapping table entry for the first portion of the memory array designated for a first usage; assigning, by the memory controller, a second granularity of a second L2P mapping table entry for the second portion of the memory array designated for a second usage, where the second granularity is not equal to the first granularity; storing, by the memory controller, the first granularity and the second granularity in the memory array; and storing, by the memory controller, at least a portion of the first L2P mapping table entry and the second L2P mapping table entry in an L2P cache of the memory controller.

In Example 10, the subject matter of Example 9 is optionally configured such that the method further comprises: partitioning, by the memory controller, the memory array to include a third portion, the first portion, second portion and third portion having non-overlapping logical block addressing (LBA) ranges; and assigning, by the memory controller, a third granularity of a third L2P mapping table entry for the third portion of the memory array designated for a third usage.

In Example 11, the subject matter of Example 10 is optionally configured such that the third granularity is not equal to the first granularity and the second granularity.

In Example 12, the subject matter of Example 10 or 11 is optionally configured such that the method further comprises: storing, by the memory controller, the third granularity in the memory array; and storing, by the memory controller, at least a portion of the third L2P mapping table entry in the L2P cache of the memory controller.

In Example 13, the subject matter of any of Examples 10-12 is optionally configured such that the method further comprises: partitioning, by the memory controller, the memory array to include a fourth portion, the first portion, second portion, third portion and fourth portion having non-overlapping logical block addressing (LBA) ranges; and assigning, by the memory controller, a fourth granularity of a fourth L2P mapping table entry for the fourth portion of the memory array designated for a fourth usage.

In Example 14, the subject matter of Example 13 is optionally configured such that the fourth granularity is not equal to the first granularity, the second granularity and the third granularity.

In Example 15, the subject matter of Example 13 or 14 is optionally configured such that the method further comprises: storing, by the memory controller, the fourth granularity in the memory array; and storing, by the memory controller, at least a portion of the fourth L2P mapping table entry in the L2P cache of the memory controller.

Example 16 is a device readable storage medium that provides instructions that, when executed by a processor, cause the processor to perform operations comprising: partitioning a memory array into a first portion and a second portion, the first portion and second portion having non-overlapping logical block addressing (LBA) ranges; assigning a first granularity of a first logical-to-physical (L2P) mapping table entry for the first portion of the memory array designated for a first usage; assigning a second granularity of a second L2P mapping table entry for the second portion of the memory array designated for a second usage, where the second granularity is not equal to the first granularity; storing the first granularity and the second granularity in the memory array; and storing at least a portion of the first L2P mapping table entry and the second L2P mapping table entry in an L2P cache.

In Example 17, the subject matter of Example 16 is optionally configured such that the first portion and the second portion are different memory types.

In Example 18, the subject matter of Example 16 or 17 is optionally configured such that partitioning the memory array into a first portion and a second portion includes partitioning the memory array at startup.

In Example 19, the subject matter of Example 16 or 17 is optionally configured such that partitioning the memory array into a first portion and a second portion includes partitioning the memory array during runtime.

In Example 20, the subject matter of Example 16 or 17 is optionally configured such that partitioning the memory array into a first portion and a second portion includes partitioning the memory array at startup and re-partitioning the memory array during runtime.

Example 21 is at least one machine-readable medium including instructions that, when executed by processing circuitry, cause the processing circuitry to perform operations to implement of any of Examples 1-20.

Example 22 is an apparatus comprising means to implement of any of Examples 1-20.

Example 23 is a system to implement of any of Examples 1-20.

Example 24 is a method to implement of any of Examples 1-20.

The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to comply with 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. 

1.-20. (canceled)
 21. A storage system, comprising: memory; and a controller configured to perform operations including: partitioning the memory into a plurality of portions having non-overlapping logical block addressing (LBA) ranges; and assigning a respective performance level to a respective logical-to-physical (L2P) mapping table entry for each of the plurality of portions of the memory, wherein at least two of the performance levels are different from each other.
 22. The storage system of claim 21, wherein at least a portion of the L2P mapping table entries is stored in an L2P cache of the controller.
 23. The storage system of claim 21, wherein the respective performance level is assigned based on a respective designated usage of each of the plurality of portions of the memory.
 24. The storage system of claim 23, wherein the plurality of portions of memory comprises a plurality of types of memory operated at different speeds.
 25. The storage system of claim 21, wherein the respective L2P mapping table entry comprises a respective granularity.
 26. The storage system of claim 25, wherein the plurality of portions comprises a first portion having a first granularity larger than a second granularity of a second portion of the plurality of portions.
 27. The storage system of claim 26, wherein a first write performance correspond to the first granularity is less than a second write performance correspond to the second granularity.
 28. The storage system of claim 27, wherein a first read performance corresponding to the first granularity is better than a second read performance corresponding to the second granularity.
 29. The storage system of claim 28, wherein the first portion has a better sequential write performance than the second portion.
 30. The storage system of claim 21, wherein the storage system comprises a NAND storage device.
 31. A method, comprising: partitioning, by a controller of a storage system, memory of the storage system into a plurality of portions having non-overlapping logical block addressing (LBA) ranges; and assigning, by the controller, a respective performance level to a respective logical-to-physical (L2P) mapping table entry for each of the plurality of portions of the memory, wherein at least two of the performance levels are different from each other.
 32. The method of claim 31, wherein the respective performance level is assigned based on a respective designated usage of each of the plurality of portions of the memory.
 33. The method of claim 31, further comprising: assigning, by the controller, a respective granularity to the respective L2P mapping table entry; and storing the respective granularity in the memory.
 34. The method of claim 33, further comprising: storing at least a portion of the L2P mapping table entries in an L2P cache of the controller.
 35. The method of claim 33, wherein the plurality of portions comprises a first portion having a first granularity larger than a second granularity of a second portion of the plurality of portions.
 36. The method of claim 35, wherein the first portion has a better sequential write performance than the second portion.
 37. A tangible non-transitory machine readable storage medium configured to store instructions, which when executed by a controller of a storage system, cause the controller to: partition memory of the storage system into a plurality of portions having non-overlapping logical block addressing (LBA) ranges; and assign a respective performance level to a respective logical-to-physical (L2P) mapping table entry for each of the plurality of portions of the memory, wherein at least two of the performance levels are different from each other.
 38. The tangible non-transitory machine readable storage medium of claim 37, wherein the storage system comprises a NAND storage device.
 39. The tangible non-transitory machine readable storage medium of claim 37, wherein the instructions further cause the controller to: assign a respective granularity to the respective L2P mapping table entry; store the respective granularity in the memory; and store at least a portion of the L2P mapping table entries in an L2P cache of the controller.
 40. The tangible non-transitory machine readable storage medium of claim 39, wherein the plurality of portions comprises a first portion having a first granularity larger than a second granularity of a second portion of the plurality of portions, and wherein the first portion has a better sequential write performance than the second portion. 